Electric incandescent lamp.



No. 819,009. PATBNTED 111311.24, 1906.

0. PBUBRLEIN. ELECTRIC INGANDBSGENT LAMP.

APPLICATION FILED JUNE14.1904.

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UNITED p STATES PATENT OFFICE.

OTTO FEUERLEIN, OF CHARLOTTENBURG, GERMANY, ASSIGNOR TO SIEMENS & HALSKE AKTIENGESELLSCHAFT, OF BERLIN,

GERMANY.

Specification of Letters Patent.

Patented April 24, 1906.

Application filed .Tune 14,1904. Serial No. 212,480.

To all whom, t may concern:

Be it known that I, OTTO FEUERLEIN, engineer, a subject of the German Emperor, residing at 17 Leibnizstrasse, Charlottenburg, near Berlin, Germany, have invented a certain new and useful Improvement in Electric Incandescent Lamps, of which the following is a full, clear, concise, and exact description.

This invention relates to improved electric incandescent lamps in which the filament consists of a refractory metal, such as tantalum or other suitable metal which possesses a comparatively low resistance as compared with copper, `and which must consequently be made of considerable length for ordinary working pressures.

Considerable difficulty is experienced if comparatively great lengths of filament are to be mounted in a relatively small glass bulb in such manner that there shall be no risk of damage to the filament or of short-circuiting in the lamp. The usual form of free-looped filaments is ot applicable, as with metal filaments of co siderable length that become soft when heated to a high temperature alterations of form and length occur, which may easily cause damage by coming in contact with the glass bulb or may cause short-circuiting in the lamp.

Hitherto when special long incandescent filaments have been used the latter have been given additional su port by being secured at several points of tiieir length by means of clamping devices or by loops through which the filament was loosely passed. This mode of treatment is, however, very expensive and unreliable and takes a long time.

According to the present invention incandescent lamps with metal filaments of considerable length that can be used in any position without detrimental variation in the length of the filament are produced in the manner hereinafter described.

In the accompanying drawings are illustrated samples of incandescent lamps with metal filaments mounted within the bulbs.

Figure 1 shows a lamp with a continuouslywound metal filament; Figs. 2 and 3, modifications thereof; Fig. 4, a modification with a filament consisting of wire sections connected by contact-pieces.

If one continuous metal filament is used, I

prefer to wind a filament of wire of the required length for yielding the necessary intensity of hght with a given pressure in a zigzag manner upon a series of supporting-arms or holding devices at suitable distances apart within a glass bulb, so as to be tightly strained between said supports. By this method the manufacture of such incandescent lamps is greatly simplified. The wires of the necessary lengths, which are kept in stock, can be very rapidly and reliably strained between the hooks of the supporting device to be fixed in the glass bulb, the support with the strained wire being then introduced into the bulb, the wire connected to an electric circuit, and the bulb exhausted in the usual manner. No other treatment of the filament is required.

Fig. 1 of the accompanying drawings shows an incandescent lam the metal filament of which is mounted in the above-described manner in the 0rlass bulb. The device a, constructed of glass or other suitable material for supporting the wire in the strained position, is composed of longitudinal and transverse bars, which latter have carrying-hooks c, of nickel or other suitable material, suitably arranged, over which vthe wire filament b is led continuously to and fro, so that it is in a strained condition between the hooks. Instead of employing hooks the wire may be passed through notches in the supporting-arms, and preferably the wire is nipped in the supports, so that it cannot shift. By this means the following advantages are obtained.

When the wire is passed free over the sup ports, a rupture 0 the wire at one point would cause the whole length of wire to become disengaged from its'support, whereas when the wire is held at the supports any such rupture at one point will not affect the parts strained between the other supports, so that repairs can be more readily eected. Furthermore, by nipping the wire any shifting thereof upon the supports in consequence of its expansion by heat is prevented. Such shifting of the wire while heated to incandescence is liable to cause it to become Welded to the support, so that on cooling it cannot shift back to its original position, and being thus subject to excessive strain at certain parts it is liable to rupture. When the wire is nipped IOO at the support, the said shifting and consequent rupture cannot occur. It has, however, been found that when the wire is nipped as described it is still liable to rupture from other cause .than that above mentioned. This disadvantage can be obviated b,y not straining the wire so tightly between the points where it is nipped when mounting it upon the supporting-frame. This can be to done by first stretching it tightlybetween the supports and then making these approach each other slightly, thereby relieving the strain on the wire; or instead of this the wire may be slightly deflected from the straight line between the supports when being mounted. The durability of the wire is greatly increased by this means. With this slight slackness of the wire, as also, generally speaking, with the elongation to which the zo Wire is subjected when heated to incandescence, there is always some risk of short-circuiting between the contiguous lengths of wire between the supports. In order to avoid this disadvantage, the wire is prefer- 2 5 ablyso mounted on the support that any two contiguous lengths thereof do not meet at an acute angle at the clamping device that holds them. This may, for example, be done as shown in Fig. 2, where a and b are two star- The filament f is led from the clamps h of star a to clamp c of star b from which, however, it does not pass direct to clamp k2 of a, but is led from 7c laterally at a right angle to 3 5 the contiguous clamp k2 of b and thence to clamp h2 of a, and so on. By this means it Will be seen that short-circuitin between the several wire sections is eectual y prevented. With vertically situated wire sections these may, however, still make short-circuiting contacts in consequence of the extension of their length and the softening thereof when heated to incandescence b the fact that, for instance, the length h2 2 when so 4.5 extended may bend laterally to the right near its lower end, while the contiguous length h3 k3 may bend laterally to the left at the lower end, when the two bends in coming in contact would form a short circuit near the clamps h2 h3. This contingency can, however, be avoided by arranging the wire sections h2 k2, &c., so that the are not parallel to the vertical center line o the stars a b, but lie obliquely thereto, as shown at Fig. 3.

With tlns oblique arrangement there are no parallel wires, so-that in no position of the amp can two wire sections assume a vertical position at the same time. It is therefore not likely to happen that the bulging of the wire sections when heated could occur in such a manner that the bulfred parts of contiguous Wires would form a shortcircuit.

Itvhas, furthermore, been found that the connecting-pieces of wire between two con- 6 5 tiguous clamps k k2 or 7c3 7a4 only become imshaped supports with clamps h h2 and lc k2.

perfectly incandescent on account of the cooling action of the clamps, in particular when these are of comparatively thick metal, as they are subject to the simultaneous cooling action of two contiguous heat-abstracting 7o conductors. Under these circumstances the said short lengths between c and k2, &c;, cause detrimental losses of pressure and energy. In order to avoid this disadvantage, it is advisable either to bridge over the lengths between 7c and 7a2, &c., by connecting to the sections in parallel a length x of a better conductor of electricity, thereby rendering the said lengths without current, or to do away entirely with the said short lengths lc 8o k2, &c., and to connect the clamps k k2 h h2, &c., by means of a thicker piece vof wire. The latter arrangement has the advantage thata considerable saving can by this means be effected in the quantity of expensive metal iilament required for a lamp. An arrangement of this kind is shown at Fig. 4, where d d2, &c., represent the connecting-conductors between the clamps le k2, &c. With the mode of construction therefore the total amount of 9o wire for incandescent lamp is cut up into separate lengths f f 2 f 3, &c., which are separately secured in a stretched condition, respectively, between two clamps of the stars a b.

The word insulating applied to the supporting means in the claims is intended to indicate that the filament is insulated thereby, but not that the entire supporting means or any particular portion of the supporting means is composed of insulating (i. e., nonroo conductive) material.

What I claim as my invention, and desire lto secure by Letters Patent, is-

1. An electric incandescent lamp comprising a continuous metallic filament, and insu- 1o 5 lating means to support the same in a plurality of substantially straight lengths or sections, each length or section being supported by said insulating means at both its end's.

2. An electric incandescent lamp comprisi 1o ing a continuous metallic filament, and a pair of insulating supporting means suitably .spaced apart, and supporting the lament in a plurality of substantially straight lengths or sections, each length or section being sup- 1.15 ported at both its ends by said insulating supporting means.

3. An electric incandescent lamp comprising a continuous metallic filament, a-nd insulating means supporting the filament in a 12o plurality of substantially straight -lengths or sections, each length or section being supported at both its ends by said insulating means, and no two lengths or sections being parallel.

4. An electric incandescent'lamp comprising two sets ofl insulating supports spaced apart, and a continuous metallic filament supported thereby in a plurality of substantially Straight lengths or sections each en- 13o gaged at both its ends by the insulating supports.

5. An electric incandescent lamp, comprising a rod, two groups of radially-extending insulating supports mounted thereon, and a continuous metallic filament supported between the two groups in a plurality of substantially straight sections, no two sections being parallel and each section being supported at both its ends by the radially-extending supports.

6. An electric incandescent lamp, comprising a glass rod, two groups of radially-projecting glass arms thereon, hooks at the outer ends of said glass arms, and a continuous metallic filament strung back and forth between the two grou s upon said hooks in substantially straight engths or sections.

7. An electric incandescent lamp, comprising a glass rod, two groups of radially-proj ecting glass arms thereon, hooks at the outer ends of said glass arms, and a continuous metallic filament strung back and forth between the two groups upon said hooks in substantially straight lengths or sections, no two lengths or sections being parallel.

' 8. An incandescent lamp comprising a rod and two groups of radially-projecting insulating-arms mounted thereon the arms of one group being in staggered relation with the arms of another group, and a continuous lament strung back and forth between the two said groups upon said arms in a plurality of substantially straight lengths or sections.

9. An electric incandescent lamp, comprising a framework having two groups of radially-projecting insulating-arms, and a continuous filament looped over said arms, the side members of each loop diverging one from the other for the purpose described.

10. An electric incandescent lamp comprising a glass rod, two groupls, of radiallyprojecting glass arms thereon t e arms of one group being in staggered relation with the arms of the other, hooks at the extremities of said arms and a continuous filament strung between the two said groups over said hooks in a plurality of straight lengths or sections.

In witness whereof I hereunto subscribe my name this 1st day of June, A. D. 1904.

OTTO FEUERLEIN.

Witnesses:

HENRY HASPER, WoLDEMAR HAUPT. 

